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Paediatric Laboratory Medicine

Craniosynostosis: Crouzon Syndrome

Clinical Significance

Craniosynostosis occurs when the bones of a baby’s skull fuse together before the brain has stopped growing. Craniosynostosis can happen before the baby is born or during the first few months of life. Fusion at one or more locations and excessive growth at others leads to the distortion of the skull. This distortion may cause increased pressure and impaired blood flow in the brain, airway obstruction, impaired vision and hearing, learning difficulties and adverse psychological effects. Deformations in the skull may also be accompanied by abnormalities in the skeletal system, often in the hands and feet. Both genetic and environmental factors contribute to craniosynostosis. Most cases that are genetic in origin arise from new mutations. Genetic craniosynostosis syndromes show autosomal dominant inheritance, meaning that an affected individual has a 50 per cent chance of passing on the mutation to their offspring, who will also be affected.

Common craniosynostosis disorders may be caused by mutations in the fibroblast growth factor receptor 1, 2 or 3 (FGFR1, FGFR2, FGFR3) genes as well as a transcription factor gene called transcription factor TWIST. The diagnosis of non-syndromic craniosynostosis is specifically based on the identification of a mutation in the fibroblast growth factor receptor 3 (FGFR3) gene. The diagnosis of Apert, Crouzon, Pfeiffer and Saethre-Chotzen Syndromes is based on clinical findings, although there is considerable clinical overlap. DNA-based testing of FGFR1 (chromosome 8p11.2-p12), FGFR2 (chromosome 10q25-q26), FGFR3 (chromosome 4p16.3), and TWIST (chromosome 7p21-p22) genes may be helpful in establishing the diagnosis in questionable cases.

Test Name

Craniosynostosis: Crouzon Syndrome

Alternate Name/ Synonym

Craniofacial dysostosis, Type I

Gene Name

  • FGFR2
  • FGFR3

Test Code



Molecular Genetics


Targeted analysis of recurrent mutations

External Proficiency Testing


Turn Around Time

2 weeks (Prenatal samples), 2-3 weeks (Pregnancy/Urgent samples), 4-6 weeks (Routine)


Fibroblast growth factor receptor 2, Fibroblast growth factor receptor 3


Craniosynostosis: Crouzon Syndrome

Specimen Type

Blood; gDNA.

If sending a prenatal sample, please contact the laboratory prior to sending sample to discuss sample requirements.

For details about specimen requirements, please refer to: Specimen Type & Requirements (PDF).

Minimum Specimen Requirements

5-10 mL EDTA or ACD 0.5 mL EDTA (neonate); minimum 10 ug in 100 uL low TE (pH8.0)


Room Temperature

Special Requirements

Special Instructions for Genome Diagnostics Samples

If sample shipment >48 hours, ship on ice.

Approval is not required

CPT Codes


Shipping and Contact Information

The Hospital for Sick Children
Rapid Response Laboratory
170 Elizabeth Street, Room 3642
Toronto, ON
M5G 2G3
Phone: 416-813-7200
Phone: 1-855-381-3212


Interpretation is provided in report

Information Sheet: Craniosynostosis